Development of a 6 GHz RF-EMF Exposure System for Investigating Human Skin Temperature Responses: Characterization, Integration, and Pilot Testing

We developed a radiofrequency electromagnetic field (RF-EMF) exposure system to investigate human skin temperature responses to localized exposures. The system was designed to project a 6 GHz RF-EMF beam with enough energy to rapidly increase peak local skin temperature on the human forearm from a baseline of 30–32°C to $\sim$ 38°C within 6 min. First, the RF-EMF exposure conditions were characterized using computer simulations to confirm that the antenna produced the desired spot size (4 cm) and resultant temperature rise in the skin. ANSYS-HFSS and Sim4Life electromagnetic and thermal simulations were performed to fully characterize the relation between electromagnetic physics and the bioheat thermal conduction problem. Next, an open-ended waveguide antenna was integrated with other hardware peripherals to comprise the full RF-EMF exposure system. Finally, human pilot testing was conducted while participants were seated comfortably with the antenna 5 cm above the skin surface on the volar (i.e. palm side) forearm. Local skin temperatures were monitored continuously with a thermal camera, which automatically identified and continuously tracked the peak skin temperature under the projected beam. Both electromagnetic and thermal data plots are presented to illustrate the bioelectromagnetic response for the exposure system. Future experimental studies using this system will examine individual and environmental factors that may influence local human skin temperature responses to RF-EMF exposures on the forearm and other body regions